After years of grilling on electric grills and little charcoal hibachis, I finally got a gas grill...a gleaming stainless steel work of art that is almost too pretty to leave out on the patio (but my wife won't let me keep it in the living room).
I usually don't get too fancy when it comes to grilling...just rub some herbs and spices on my meat (no pun intended) and throw it on the grill. The food always turned out pretty much the same: tasty, but nothing exceptional.
So: anyone have a great marinade they swear by which they wouldn't mind sharing?
Last night I used the new grill for the first time (and first time ever cooking on a gas grill), and I was so impatient that I didn't wait for the steaks to thaw thoroughly. Well, when I thought they were done they were beautiful on the outside, but were still frozen in the middle. Five minutes later the middle was still cold, but not frozen. Five more minutes and the steaks were very well done. (I hate well-done.)

There is nothing better, or easier then letting a steak marinade in beer.
Use a pale beer like Rolling Rock
Soak it for a couple of hours before you grill it.
It adds a great flavor, and makes meat really tender.

The best marinade for chicken or pork, is brine.
AKA salt water.
Try it.
For beef?
I only marinate london broils. A truly good steak shouldn't be smothered in sauces of marinades.
For london broil:
Ginger
Garlic
Soy Sauce.
(sprinkle meat with brown sugar before cooking)
Pork Ribs?
Salt and pepper, then SLOW cook.
If you know how to cook, you don't need sauces.
Once you learn, then maybe get creative.
But first learn how to properly roast and grill meat.

I still like rubs for most cuts. London Broil I marinate in italian dressing.
The nice thing about the bigger grill is now you can go for the bigger cuts like whole briskets, whole ribs, tri-tips etc. Don't fergit that when yah close the lid yah really add the oven effect you don't get on a small open grill.
And as you learned you really gotta make sure it is room temp all the way. You don't do that with a tri-tip and the outside is way past being done and the middle is still cold.